PROJECT SUMMARY/ABSTRACT Status epilepticus affects approximately 160,000 people in the U.S. each year and carries substantial associated morbidity and mortality. Use of prehospital benzodiazepines by EMS providers varies widely, resulting in failures to provide evidence-based care to a large proportion of patients. Despite the striking underuse of prehospital benzodiazepines for status epilepticus, the causes and the clinical consequence have not been fully delineated. Prehospital providers may hesitate to administer benzodiazepines because the respiratory risks of undertreated seizures may be perceived as less morbid than the respiratory depression caused by medication-related oversedation. Alternatively, prehospital care may be driven by variable emergency medical services treatment protocols that frequently define status epilepticus incorrectly and instruct providers to give benzodiazepine doses lower than established guidelines. Accordingly, the overall objective of this proposal is to discover the key factors that dictate prehospital status epilepticus management and quantify the extent to which our current shortcomings are associated with worse outcomes. The advent of more detailed EMS electronic medical records and linkage of these records to hospital data provide a new opportunity to examine these questions with increased rigor. The results will be critical in addressing the clinical concerns of front-line providers and improving outcomes among patients with status epilepticus through the following specific aims: Aim 1. Assess the association between undertreated status epilepticus and clinical outcomes. Aim 2. Determine the association between prehospital benzodiazepine dose and EMS agency protocol instructions for status epilepticus. Aim 3. Identify barriers and facilitators to evidence-based benzodiazepine administration for patients with out- of-hospital status epilepticus using qualitative methods. Through the proposed research, relevant coursework, and a mentoring team with wide-ranging expertise, Dr. Guterman will build necessary skills in study design and advanced biostatistical methods (Dr. Daniel Lowenstein, the primary mentor, and Dr. John Neuhaus), implementation science (Dr. S. Andrew Josephson and Dr. Sara Ackerman), and qualitative and mixed methods research (Dr. Sara Ackerman). The findings from this project will address an understudied aspect of status epilepticus care and provide insight needed to improve its prehospital treatment. The results will build the evidence base for a future R01 proposal to prospectively evaluate prehospital treatment and outcomes in patients presenting with status epilepticus. This project will also bring Dr. Guterman closer to her long-term goal of becoming a leading clinician-investigator dedicated to advancing the treatment of status epilepticus and ensuring that real-world care for these patients matches the best available evidence.